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fix: EZBC for TAV producing dark bloches on white background due to coeff clipping

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minjaesong
2025-11-11 03:22:10 +09:00
parent 9425c58e53
commit bff5021a7a
3 changed files with 104 additions and 58 deletions
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36
video_encoder/encoder_tav.c
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@@ -1976,7 +1976,7 @@ typedef struct tav_encoder_s {
int two_pass_mode; // Enable two-pass encoding (0=disabled, 1=enabled)
frame_analysis_t *frame_analyses; // Array of frame analysis metrics (first pass)
int frame_analyses_capacity; // Allocated capacity
int frame_analyses_count; // Current number of analyzed frames
int frame_analyses_count; // Current number of analysed frames
gop_boundary_t *gop_boundaries; // Linked list of GOP boundaries (computed in first pass)
gop_boundary_t *current_gop_boundary; // Current GOP being encoded (second pass)
int two_pass_current_frame; // Current frame number in second pass
@@ -6702,13 +6702,22 @@ static void quantise_dwt_coefficients_perceptual_per_coeff_no_normalisation(tav_
// Step 3: Round to discrete quantisation levels
quantised_val = roundf(quantised_val); // file size explodes without rounding
// Step 4: Denormalise - multiply back by quantiser to restore magnitude
// This gives us quantised values at original scale (not shrunken to 0-10 range)
float denormalised = quantised_val * effective_q;
// FIX: Store normalised values (not denormalised) to avoid int16_t overflow
// EZBC bitplane encoding works fine with normalised coefficients
// Denormalisation was causing bright pixels to clip at 32767
quantised[i] = (int16_t)CLAMP((int)quantised_val, -32768, 32767);
// CRITICAL FIX: Must round (not truncate) to match decoder behavior
// With odd baseQ values and fractional weights, truncation causes mismatch with Sigmap mode
quantised[i] = (int16_t)CLAMP((int)roundf(denormalised), -32768, 32767);
// Debug: Print LL subband coefficients (9×7 at top-left for 560×448)
static int debug_once = 1;
if (debug_once && i < 63 && width == 560 && !is_chroma) {
int x = i % width;
int y = i / width;
if (x < 9 && y < 7) {
fprintf(stderr, "[EZBC-QUANT-DEBUG] LL coeff[%d,%d] (idx=%d): coeff=%.1f, weight=%.3f, effective_q=%.1f, quantised_val=%.1f, stored=%d\n",
x, y, i, coeffs[i], weight, effective_q, quantised_val, quantised[i]);
if (i == 62) debug_once = 0;
}
}
}
}
@@ -9631,7 +9640,7 @@ static void free_gop_boundaries(gop_boundary_t *head) {
}
}
// First pass: Analyze all frames and build GOP boundaries
// First pass: Analyse all frames and build GOP boundaries
// Returns 0 on success, -1 on error
static int two_pass_first_pass(tav_encoder_t *enc, const char *input_file) {
printf("=== Two-Pass Encoding: First Pass (Scene Analysis) ===\n");
@@ -9737,12 +9746,12 @@ static int two_pass_first_pass(tav_encoder_t *enc, const char *input_file) {
frame_num++;
if (frame_num % 100 == 0) {
printf(" Analyzed %d frames...\r", frame_num);
printf(" Analysed %d frames...\r", frame_num);
fflush(stdout);
}
}
printf("\n Analyzed %d frames total\n", frame_num);
printf("\n Analysed %d frames total\n", frame_num);
free(frame_rgb);
if (prev_dwt) free(prev_dwt);
@@ -9881,7 +9890,7 @@ int main(int argc, char *argv[]) {
{"adaptive-blocks", no_argument, 0, 1022},
{"bframes", required_argument, 0, 1023},
{"gop-size", required_argument, 0, 1024},
{"ezbc", no_argument, 0, 1025},
{"sigmap", no_argument, 0, 1025},
{"separate-audio-track", no_argument, 0, 1026},
{"pcm8-audio", no_argument, 0, 1027},
{"pcm-audio", no_argument, 0, 1027},
@@ -10095,9 +10104,8 @@ int main(int argc, char *argv[]) {
}
printf("GOP size set to %d frames\n", enc->residual_coding_gop_size);
break;
case 1025: // --ezbc
enc->preprocess_mode = PREPROCESS_EZBC;
printf("EZBC (Embedded Zero Block Coding) enabled for significance maps\n");
case 1025: // --sigmap
enc->preprocess_mode = PREPROCESS_TWOBITMAP;
break;
case 1026: // --separate-audio-track
enc->separate_audio_track = 1;